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    <title>Document</title>
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<body>
    <script>
        var permute = function (nums) {
            let res = []
            let path = []
            let used = new Array(nums.length).fill(0)
            function backtracking(nums, used) {
                if (path.length === nums.length) {
                    res.push([...path])
                }
                for (let i = 0; i < nums.length; i++) {
                    if (used[i]) continue
                    used[i] = true
                    path.push(nums[i])
                    backtracking(nums, used)
                    used[i] = false
                    path.pop()
                }
            }
            backtracking(nums, used)
            return res
        };
        console.log(permute([1, 2, 3]));
    </script>
</body>

</html>